It's a law that sets two of Australia's states apart from the rest of the country.
In Tasmania, Queensland, WA and SA - and in the ACT and Northern Territory - people of all ages are allowed to ride bicycles on the footpath unless otherwise indicated.
But in NSW and Victoria, if you're aged 12 or over, it's against the law except in certain circumstances, such as an adult accompanying a rider under the age of 12 (here are the rules for NSW and Victoria).
A few years ago there was a 50/50 split between jurisdictions – but since then, South Australia and Western Australia have eased their regulations.
And cycling organisations are campaigning for NSW and Victoria to do the same.
Last month, Bicycle NSW announced it would push for all-ages riding on footpaths, following a survey that showed NSW had the lowest level of cycling participation in the country and in the wake of a number of cyclist deaths and serious injuries on the state's roads.
"There needs to be a change in the current cycling environment in NSW," said CEO Craig Meagher in a statement.
"Children are being forced to ride on the road at the age of 12. Adults who are rediscovering bike riding are being left with no option but to battle the roads. This is not an environment that encourages bike riding."
Bicycle Network, the nation's largest cycling organisation, is also calling for the rules to change.
"Not all of our roads have appropriate bike infrastructure or places to ride," its campaign says. "Allowing adults to ride on the footpath means that less confident riders can avoid pinch points and merging with traffic, reducing their risk."
Like many cycling topics, the issue of footpath riding in Australia is both complex and controversial. Here are a few things to consider:
Forcing 12-year-olds onto roads
The most contentious aspect of the laws in Victoria and NSW must surely be that when a child turns 12, they can no longer ride on the footpath.
Sydney father Callum Gordon is running an online petition asking the NSW government to re-examine this rule, as he is concerned about the safety implications once his children get older.
"My children are increasingly cycling and for me that's great for many reasons," he told Fairfax Media, saying a law ordering 12-year-olds off the footpath was "crazy".
States that recently changed
In South Australia, all-ages footpath riding was legalised in October 2015. The changes followed the recommendations of a "citizens' jury" on road safety issues.
The move proved controversial, especially after media reports of two pedestrians being injured in collisions with cyclists shortly after the change.
So how has it been going since then? A spokesperson for the SA Transport Department said there is limited data available and "at least five years of data would generally be analysed before and after a road safety initiative to determine changes".
However, five months after the new rules were put in place, the SA police commissioner told a parliamentary inquiry: "We haven't seen any big trends of lycra-wearing cyclists jumping on the footpaths and travelling at 30 or 40km/h."
In WA, allowing adults to ride on footpaths was announced as "a common-sense change" in April 2016 by then roads minister Liza Harvey, who said the move followed extensive consultation, including a Cycling Safety Roundtable.
Victoria Walks and the Pedestrian Council of Australia said they would fight any attempt to change the laws in the two states.
Dr Ben Rossiter of Victoria Walks said his organisation was "totally opposed to any further increase in cycling on footpaths", adding that footpaths are too narrow and not designed for cycling, which would put aged pedestrians at risk.
Meanwhile, riding on the footpath carries hazards for cyclists, such as vehicles coming out of driveways, and a law change could provide an excuse to stop building infrastructure, Rossiter said.
Robyn Seymour of VicRoads said: "Allowing extra cyclists and bike traffic on the footpath creates a greater risk for pedestrians, particularly children, the elderly and people living with a disability."
And a Transport for NSW spokesperson said: "While there are only a small number of recorded crashes between bicycles and pedestrians each year, nevertheless it is the pedestrian who is generally at a greater risk of serious injury."
'An intimidating place'
One common observation is that Victoria and NSW have areas of high population density that are incompatible with footpath riding. However, a counter-argument is that a busy footpath will likely slow or deter any riders, while less-dense areas often have quiet footpaths - and busy arterial roads that are hard to circumvent.
Meanwhile, sports cyclists regularly prefer roads to designated shared-use paths that run alongside, in order to travel swiftly without conflicts with pedestrians.
Despite the rules, I see riders on footpaths in Sydney almost every day. Most appear to be transport cyclists who are avoiding busy roads - while risking a $110 fine.
"Unfortunately, the road can be an intimidating place for inexperienced riders, seniors and women," Bicycle NSW says. "Providing a safe zone for these riders will encourage them to ride more and further, improving their health. Where segregated cycleways are not provided, having the footpath that they can safely share with pedestrians should be a viable option."
Bicycle Network argues that "it not only works in other states, there's also plenty of local examples where bike riders and pedestrians share spaces and paths coherently".
Fairfax journalist Michael O'Reilly has written the On Your Bike blog since 2011.